Prenatal diagnosis and molecular cytogenetics in a case of partial trisomy14 and monosomy 21

We report an unbalanced translocation involving chromosomes 14 and 21 which presented as fetal ventriculomegaly at 33 weeks gestation. Second trimeste r ultrasound had indicated normal fetal anatomy, including normal intracran ial structures. Parental karyotypes showed a paternal balanced translocatio n: 46,XY,t(14;21)(q12;q21). The unbalanced translocation in the fetus resul ted in trisomy for 14pter --> q12 and monosomy for 21pter --> q21. Postnata l examination showed that the male infant had a cleft palate, but no cleft lip, and mild dysmorphic features. Postnatal MRI revealed bilateral and sym metric dilatation of the occipital horns, atria, and temporal horns of the lateral ventricles. Molecular cytogenetic techniques were used to delineate further the breakpoint on chromosome 14 to a site distal of the D14S1071 l ocus and the breakpoint on chromosome 21 to a region between D21S1918 and D 21S1902. More precise definitions of chromosomal breakpoints in such clinic al cases should provide more accurate prognosis for individuals with unbala nced karyotypes and assist in the identification of putative developmentall y important genes. (C) 2001 Wiley-Liss, Inc.